From 30481a5a9e3e42cde1cb9d999d4038da646404b4 Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@element.io>
Date: Wed, 3 Mar 2021 11:51:50 +0100
Subject: [PATCH] add logging to key sharing and discarding in reaction to
 member changes

---
 src/matrix/e2ee/RoomEncryption.js | 15 ++++++++++++---
 src/matrix/room/Room.js           |  2 +-
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/matrix/e2ee/RoomEncryption.js b/src/matrix/e2ee/RoomEncryption.js
index 9a6a5fc3..59994c0f 100644
--- a/src/matrix/e2ee/RoomEncryption.js
+++ b/src/matrix/e2ee/RoomEncryption.js
@@ -79,14 +79,18 @@ export class RoomEncryption {
         this._senderDeviceCache = new Map();    // purge the sender device cache
     }
 
-    async writeMemberChanges(memberChanges, txn) {
+    async writeMemberChanges(memberChanges, txn, log) {
         let shouldFlush;
         const memberChangesArray = Array.from(memberChanges.values());
         if (memberChangesArray.some(m => m.hasLeft)) {
+            log.log({
+                l: "discardOutboundSession",
+                leftUsers: memberChangesArray.filter(m => m.hasLeft).map(m => m.userId),
+            });
             this._megolmEncryption.discardOutboundSession(this._room.id, txn);
         }
         if (memberChangesArray.some(m => m.hasJoined)) {
-            shouldFlush = await this._addShareRoomKeyOperationForNewMembers(memberChangesArray, txn);
+            shouldFlush = await this._addShareRoomKeyOperationForNewMembers(memberChangesArray, txn, log);
         }
         await this._deviceTracker.writeMemberChanges(this._room, memberChanges, txn);
         return shouldFlush;
@@ -310,11 +314,16 @@ export class RoomEncryption {
         await removeOpTxn.complete();
     }
 
-    async _addShareRoomKeyOperationForNewMembers(memberChangesArray, txn) {
+    async _addShareRoomKeyOperationForNewMembers(memberChangesArray, txn, log) {
         const userIds = memberChangesArray.filter(m => m.hasJoined).map(m => m.userId);
         const roomKeyMessage = await this._megolmEncryption.createRoomKeyMessage(
             this._room.id, txn);
         if (roomKeyMessage) {
+            log.log({
+                l: "share key for new members", userIds,
+                id: roomKeyMessage.session_id,
+                chain_index: roomKeyMessage.chain_index
+            });
             this._writeRoomKeyShareOperation(roomKeyMessage, userIds, txn);
             return true;
         }
diff --git a/src/matrix/room/Room.js b/src/matrix/room/Room.js
index 6f8c7530..cc325aa4 100644
--- a/src/matrix/room/Room.js
+++ b/src/matrix/room/Room.js
@@ -256,7 +256,7 @@ export class Room extends EventEmitter {
         let shouldFlushKeyShares = false;
         // pass member changes to device tracker
         if (roomEncryption && this.isTrackingMembers && memberChanges?.size) {
-            shouldFlushKeyShares = await roomEncryption.writeMemberChanges(memberChanges, txn);
+            shouldFlushKeyShares = await roomEncryption.writeMemberChanges(memberChanges, txn, log);
             log.set("shouldFlushKeyShares", shouldFlushKeyShares);
         }
         // also apply (decrypted) timeline entries to the summary changes